U.S. Pat. No. 2,820,778 describes a catalyst wherein an alkyl or cycloalkyl distannoxane combined with a Group IVB, Group VB or Group VIB transition metal halide is used to polymerize olefins. However, these combinations produce polymeric products in relatively low yield and hence are of limited value.
British Pat. No. 887,544 entitled Process for Polymerizing Propylene teaches use of a hydrocarbon insoluble, brown precipitate formed from, e.g., a tetraalkyltin, titanium tetrachloride and aluminum chloride in conjunction with an organometallic activator, e.g., a trialkylaluminum, for polymerization of propylene. The presence of aluminum chloride reactant is required to get the brown hydrocarbon insoluble component of the British patent.
Now it has been found that by combining certain Group IVB, Group VB or Group VIB transition metal compounds with an organotin compound by reaction of the former with an OH group of the latter, highly active catalyst systems which are relatively insensitive to chain terminating agents such as hydrogen are formed.